NAND: Add 16bit NAND support for the NDFC

This patch adds support for 16 bit NAND devices attached to the
NDFC on ppc4xx processors. Two config entries were added:

  CONFIG_SYS_NDFC_16        - Setting this tells the NDFC that a
			      16 bit device is attached.
  CONFIG_SYS_NDFC_EBC0_CFG  - This is for the External Bus
			      Controller configuration register.

Also, a new ndfc_read_byte() function was added which does not
first convert the data to little endian.

The NAND SPL was also modified to do 16bit bad block testing
when a 16 bit chip is being used.

Signed-off-by: Alex Waterman <awaterman@dawning.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>
diff --git a/README b/README
index 446966d..a760cf3 100644
--- a/README
+++ b/README
@@ -2917,6 +2917,14 @@
 - CONFIG_SYS_SRIOn_MEM_SIZE:
 		Size of SRIO port 'n' memory region
 
+- CONFIG_SYS_NDFC_16
+		Defined to tell the NDFC that the NAND chip is using a
+		16 bit bus.
+
+- CONFIG_SYS_NDFC_EBC0_CFG
+		Sets the EBC0_CFG register for the NDFC. If not defined
+		a default value will be used.
+
 - CONFIG_SPD_EEPROM
 		Get DDR timing information from an I2C EEPROM. Common
 		with pluggable memory modules such as SODIMMs